It is well-know that immobilized persons experience skin ulcerations, or pressure sores, which occur when the skin is subjected to external pressure for prolonged periods. The increased tissue pressure results in reduced oxygen delivery to the tissue and ultimately to the development of ulcers in the muscle, skin and connective tissue. Ischemic skin ulcers also result from chronic venous stasis, peripheral arterial insufficiency (as in diabetics), certain infections, venomous bites, sickle cell anemia, and numerous other pathophysiologic and physical factors.
Conventional methods for treating soft tissue wounds include applications of various ointments or medicaments to aid the natural body healing process. Another method is to relieve the pressure which caused the sore. A variety of mattresses, beds, wheelchair cushions and other pads have been devised to reduce pressure or distribute pressure more evenly over the body. However, it has been found that some wounds, including chronic wounds, do not respond to conventional treatment methods and resist healing.
It has been reported in the literature that healing of soft tissue wounds can be accelerated through use of electrical stimulation. Some researches have reported beneficial and reproducible healing when other treatment methods have failed. The result of some prior studies are summarized in Table 1 below:
TABLE 1 __________________________________________________________________________ CLINICAL STUDIES Hrs. of Avg. # Type & Total of Wks. Healing Journal/ Number Number Type of Treatment Req. for Rate Investigator Patients of Ulcers Treatment Time/Wk. Healing Per Wk. __________________________________________________________________________ Assimacopoulos 3 6 (venous low intensity 168 4.4 (1968) stasis) DC (75-100 Am. J. Surg. microamp) Wolcott et. al. 67 8:control low intensity 42 9.5 13.4%/wk (1969) 75:treatment DC healing rate vs. Southern Med. J. (Ischemic (approx 600 5% per week ulcers) microamp) for controls Gault & Gatens 76 6:control low intensity 42 4.7 30%/wk (1976) 100:treatment DC (200-1000 healing rate vs. Phys. Ther. (Ischemic microamp) 14.7%/wk for ulcers) controls Cartey & 30 15:control low intensity 20 5 17.9%/wk Wainapel 15:treatment DC (300-700 healing rate vs. (1975) (Indolent microamp) 9%/wk for Arch. Phys. Med. ulcers) controls Barron, et. al. 6 6 decubitus Biphasic 3 4 (1985) ulcers pulses 600 Minn. Med. (resisted microamp treatment up at 0.5 Hz to 1 yr.) w/electronic waveform control Alon, et. al. 15 15 diabetic high voltage 3 11.3 (1986) ulcers short duration Phys. Ther. (persisted for pulses avg. 8.6 mos.) (80 Hz) Feedar & Kloth 8 3:control high voltage 3.7 7.3 25.3% per healing (1985) 5:treatment short duration weekrate Phys. Ther. (stage IV (60 microsec. w/increased decubitus pulses) control would ulcers) size __________________________________________________________________________
Electrical stimulation is generally applied by the use of two electrodes, referred to as the active electrode and the dispersive electrode. The active electrode is usually applied directly over the soft tissue wound, or is immersed in a saline solution into which the body part is also placed. In either case, the dispersive electrode, or return electrode, is positioned in contact with the body of the patient as far as possible from the wound.
Prior methods of treatment using electrical stimulation have several disadvantages. First, prior treatment methods call for application of an electrical stimulation to the patient's body over long periods of time. Most of these prior art treatment methods call for current being applied over periods from between thirty minutes to several hours. Since most patients will have more than one sore, the prior art methods are not very practical due to the time it takes to treat each sore.
Another drawback of prior art methods is that some patients have experienced pain during application of the electrical stimulation. The pain is caused by an acid or base buildup on the electrodes used to apply the electrical stimulation to the patient's body. These acid and base buildups can burn the patient's skin and cause the treatment to be very painful.
Also, past treatment methods have utilized electrodes having relatively large surface areas which are applied directly over the sore by direct pad application. The direct pad application to the sore is a source for bacterial contamination which can complicate treatment of the sore.